This invention relates to a braking device for an elevator winding machine and an elevator using the braking device. More particularly, the invention relates to a braking device for an elevator winding machine, wherein a brake section is elasticilly supported in the rotating direction, and to an elevator using the braking device.
In an elevator, a car or cage and a balance weight are generally suspended from a sheave of a motor-driven winding machine through a rope or cable, to one end of which the car is attached and to another end of which the balance weight is attached. While the elevator is not being moved, the braking device is actuated and an unbalance torque generated by a difference in weight between the car and the balance weight is absorbed by the braking device. If, under this condition, the braking device is released and the elevator is operated, the unbalance torque, generates a starting shock.
In order to decrease the starting shock when the elevator is started, in a conventionally-practiced method, the motor generates at first a torque (starting compensation torque) corresponding to the braking torque (unbalance torque) which has been generated by the braking device, and subsequently the braking device is released.
To perform the starting compensation as mentioned above, it is necessary to detect the braking torque corresponding to the unbalance torque when the elevator car is not being moved.
In the conventional method for detecting the braking torque, the brake section, of the braking device is supported through the intermediary of an elastic body and a displacement of the brake section in its rotating direction is detected. (Japanese Patent Unexamined Publication No. 57-1180).
In the braking device for an elevator winding machine, which has a construction as described above, if a spring constant of the elastic body is small to improve the braking torque detecting accuracy, the elastic body is greatly deformed by a very small braking torque so that the brake section rotates by a predetermined angle.
However, when the elevator car receives many passengers almost to its riding capacity and a large braking torque is needed, the elastic body is deformed greatly so that the brake section collides against a stopper, and a shock generated at this time terrifies the passengers in the car.
On the other hand if the spring constant of the elastic body is large in order to prevent the brake section from colliding against the stopper, the detecting accuracy of the braking torque is lowered so that the starting compensation can not be executed adequately.